In a store such as a supermarket, a customer walks around in the store while looking at a commodity. The customer looks at a commodity, to take an interest in the commodity. The customer takes an interest in the commodity, to have a desire to acquire the commodity. The customer may come to purchase the commodity through these stages. For the reason, the store analyzes an image imaged by a camera installed in the store, to grasp a flow line of a customer walking around in the store. The store judges a commodity arranged along the grasped flow line to be a commodity in which the customer is interested. The store tries to promote a commodity judged to be the commodity in which the customer is interested, to the customer.
However, only grasping a flow line of a customer is insufficient for grasping a commodity in which the customer is interested.